Malaria research and field research sites

Thailand is a malaria-endemic country, where all human malaria species, P. falciparum, P. vivax, P. malariae, and P. ovale, have been found. Cross-border migration is a major cause of malaria transmission in the region. Drug-resistant parasites, both P. falciparum and P. vivax, have been reported in the country. The MVRC lab studies the biology and transmission of human malaria parasites, mosquito vectors and uses in vitro/ex vivo systems to conduct research to support new drugs and vaccine development.

The MVRC has established laboratories in endemic areas, in Kanchanaburi and Tak provinces, where specific research can be conducted in high malaria-transmission areas. In collaboration with the Entomology Department, Faculty of Tropical Medicine, Mahidol University, vectors for malaria have been provided for studies at the MVRC. Combined with the capability to perform in vitro culture of human liver cells, MVRC scientists can study the complete life cycle of human malaria parasites.

Current research activities at MVRC
  • Long-term continuous culture of blood-stage P. vivax: this study is a collaboration with the University of South Florida, USA (PI), the MVRC, Walter and Eliza Hall Institute of Medical Research, Australia (WEHI) and Nagasaki University, Japan. The goal is to establish an easy protocol for continuous culture of P. vivax blood-stage parasites producing infective gametocytes. This study has been funded by The Bill & Melinda Gates Foundation (BMGF).
  • Transcriptome and proteomic study of P. vivax sporozoites and liver-stage parasites.
  • Evaluation of transmission blocking-vaccine efficacy: This study uses the full range of expertise available at the MVRC field laboratory, along with the availability of mosquitoes from the insectary and access to malaria infected patients from the local area to perform ex vivo evaluation of transmission-blocking vaccine efficacy. Our group has focused on P. vivax while P. falciparum will be tested as a comparison to African P. falciparum.
  • Comparative epidemiology of P. falciparum and P. vivax transmission: This study aims to determine the dynamics of malaria transmission stages in host and vectors, determine bottlenecks and their impact in transmission and parasite population diversity in different endemic areas. In collaboration with Mahidol University, CRESIB-Spain, IMR-Papua New Guinea and Medicina Tropical do Amazonas, Manaus, Brazil. This study has been funded by The Bill & Melinda Gates Foundation.
  • Southeast Asia Malaria Research Center: As part of the International Center of Excellence for Malaria Research, funded by the National Institutes of Health (NIH), USA, this study aims to develop an accurate measurement of the heterogeneity of the malaria burden and provide essential epidemiological information for developing and evaluating integrated malaria-control strategies in multiple sites with varying epidemiological conditions.
  • Evaluation of loop-mediated isothermal amplification (LAMP) for malaria diagnosis.
  • The study of P. vivax liver-stage biology and malaria transmission in Asia.
Transmission-blocking Vaccines (TBV)
General features of malaria transmission and transmission blocking vaccines

The effect of TBV-induced immunity is to prevent the fertilization or the subsequent development of malaria parasites in the mosquito midgut. As a consequence, the formation of oocysts, and ultimately of infective sporozoites in the mosquito salivary glands is prevented or reduced. This leads to a fall in entomological infection rates (EIR) and basic reproductive number (R0) within a community.

Goals of vaccination
  • Prevent disease by blocking infection before emergence from liver.
  • Reduce disease by a vaccine that combines partially effective pre-erythrocytic and blood-stage components.
  • Reduce disease by reducing blood-stage asexual parasite burden.
Evaluation of TBV by Membrane Assay at MVRC
The efficacy of a TBV is defined at the following levels of evaluation
  • Reduction in the proportion of mosquitoes that become infected when fed through a membrane upon gametocytes in the presence of sera taken from TBV-vaccinated individuals.
  • Reduction in the proportion of mosquitoes that become infected when fed directly upon TBV-vaccinated individuals following natural infection.
  • Reduction in the incidence of malarial infections – e.g. incidence of clinical cases or parasite prevalence in a TBV-vaccinated community.
In a TBV- vaccinated population:

The R0 will be reduced in proportion to the effective coverage by the vaccine.